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  • NSUserDefaults not present on first run on simulator

    - by Ben Collins
    I've got some settings saved in my Settings.bundle, and I try to use them in application:didFinishLaunchingWithOptions, but on a first run on the simulator accessing objects by key always returns nil (or 0 in the case of ints). Once I go to the settings screen and then exit, they work fine for every run thereafter. What's going on? Isn't the point of using default values in the Settings.bundle to be able to use them without requiring the user to enter them first?

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  • Entity Framework in n-layered application - Lazy loading vs. Eager loading patterns

    - by Marconline
    Hi all. This questions doesn't let me sleep as it's since one year I'm trying to find a solution but... still nothing happened in my mind. Probably you can help me, because I think this is a very common issue. I've a n-layered application: presentation layer, business logic layer, model layer. Suppose for simplicity that my application contains, in the presentation layer, a form that allows a user to search for a customer. Now the user fills the filters through the UI and clicks a button. Something happens and the request arrives to presentation layer to a method like CustomerSearch(CustomerFilter myFilter). This business logic layer now keeps it simple: creates a query on the model and gets back results. Now the question: how do you face the problem of loading data? I mean business logic layer doesn't know that that particular method will be invoked just by that form. So I think that it doesn't know if the requesting form needs just the Customer objects back or the Customer objects with the linked Order entities. I try to explain better: our form just wants to list Customers searching by surname. It has nothing to do with orders. So the business logic query will be something like: (from c in ctx.CustomerSet where c.Name.Contains(strQry) select c).ToList(); now this is working correctly. Two days later your boss asks you to add a form that let you search for customers like the other and you need to show the total count of orders created by each customer. Now I'd like to reuse that query and add the piece of logic that attach (includes) orders and gets back that. How would you front this request? Here is the best (I think) idea I had since now. I'd like to hear from you: my CustomerSearch method in BLL doesn't create the query directly but passes through private extension methods that compose the ObjectQuery like: private ObjectQuery<Customer> SearchCustomers(this ObjectQuery<Customer> qry, CustomerFilter myFilter) and private ObjectQuery<Customer> IncludeOrders(this ObjectQuery<Customer> qry) but this doesn't convince me as it seems too complex. Thanks, Marco

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  • Django : presenting a form very different from the model and with multiple field values in a Django-

    - by sebpiq
    Hi ! I'm currently doing a firewall management application for Django, here's the (simplified) model : class Port(models.Model): number = models.PositiveIntegerField(primary_key=True) application = models.CharField(max_length=16, blank=True) class Rule(models.Model): port = models.ForeignKey(Port) ip_source = models.IPAddressField() ip_mask = models.IntegerField(validators=[MaxValueValidator(32)]) machine = models.ForeignKey("vmm.machine") What I would like to do, however, is to display to the user a form for entering rules, but with a very different organization than the model : Port 80 O Not open O Everywhere O Specific addresses : --------- delete field --------- delete field + add address field Port 443 ... etc Where Not open means that there is no rule for the given port, Everywhere means that there is only ONE rule (0.0.0.0/0) for the given port, and with specific addresses, you can add as many addresses as you want (I did this with JQuery), which will make as many rules. Now I did a version completely "handmade", meaning that I create the forms entirely in my templates, set input names with a prefix, and parse all the POSTed stuff in my view (which is quite painful, and means that there's no point in using a web framework). I also have a class which aggregates the rules together to easily pre-fill the forms with the informations "not open, everywhere, ...". I'm passing a list of those to the template, therefore it acts as an interface between my model and my "handmade" form : class MachinePort(object): def __init__(self, machine, port): self.machine = machine self.port = port @property def fully_open(self): for rule in self.port.rule_set.filter(machine=self.machine): if ipaddr.IPv4Network("%s/%s" % (rule.ip_source, rule.ip_mask)) == ipaddr.IPv4Network("0.0.0.0/0"): return True else : return False @property def partly_open(self): return bool(self.port.rule_set.filter(machine=self.machine)) and not self.fully_open @property def not_open(self): return not self.partly_open and not self.fully_open But all this is rather ugly ! Do anyone of you know if there is a classy way to do this ? In particular with the form... I don't know how to have a form that can have an undefined number of fields, neither how to transform these fields into Rule objects (because all the rule fields would have to be gathered from the form), neither how to save multiple objects... Well I could try to hack into the Form class, but seems like too much work for such a special case. Is there any nice feature I'm missing ?

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  • Programming Logic upgrading from VB6 to Vb.net

    - by KoolKabin
    Hi guys, I have been programming in vb6 for few time ago and i used open SQL Server connection and command objects to make database traansactions. I have been searching for similar approaches in vb.net too but not finding any starting point. How can we work similarly in vb.net application?

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  • Convert array of hashes to array of structs?

    - by keruilin
    Let's say I have two objects: User and Race. User has two attributes: first_name, last_name. And Race has three attributes: course, start_time, end_time. Now let's say I create an array of hashes like this: user_races = races.map{ |race| {:user = race.user, :race = race} } How do I then convert user_races into an array of structs, keeping in mind that I want to be able to access the attributes of both user and race from the struct element?

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  • inner class within Interface

    - by harigm
    is that possible to create a inner class within an interface? If yes, why do we create like that? Anyways we are not going to create any interface objects? Do they help in any Development process?

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  • How to use objetcs as modules/functors in Scala?

    - by Jeff
    Hi. I want to use object instances as modules/functors, more or less as shown below: abstract class Lattice[E] extends Set[E] { val minimum: E val maximum: E def meet(x: E, y: E): E def join(x: E, y: E): E def neg(x: E): E } class Calculus[E](val lat: Lattice[E]) { abstract class Expr case class Var(name: String) extends Expr {...} case class Val(value: E) extends Expr {...} case class Neg(e1: Expr) extends Expr {...} case class Cnj(e1: Expr, e2: Expr) extends Expr {...} case class Dsj(e1: Expr, e2: Expr) extends Expr {...} } So that I can create a different calculus instance for each lattice (the operations I will perform need the information of which are the maximum and minimum values of the lattice). I want to be able to mix expressions of the same calculus but not be allowed to mix expressions of different ones. So far, so good. I can create my calculus instances, but problem is that I can not write functions in other classes that manipulate them. For example, I am trying to create a parser to read expressions from a file and return them; I also was trying to write an random expression generator to use in my tests with ScalaCheck. Turns out that every time a function generates an Expr object I can't use it outside the function. Even if I create the Calculus instance and pass it as an argument to the function that will in turn generate the Expr objects, the return of the function is not recognized as being of the same type of the objects created outside the function. Maybe my english is not clear enough, let me try a toy example of what I would like to do (not the real ScalaCheck generator, but close enough). def genRndExpr[E](c: Calculus[E], level: Int): Calculus[E]#Expr = { if (level > MAX_LEVEL) { val select = util.Random.nextInt(2) select match { case 0 => genRndVar(c) case 1 => genRndVal(c) } } else { val select = util.Random.nextInt(3) select match { case 0 => new c.Neg(genRndExpr(c, level+1)) case 1 => new c.Dsj(genRndExpr(c, level+1), genRndExpr(c, level+1)) case 2 => new c.Cnj(genRndExpr(c, level+1), genRndExpr(c, level+1)) } } } Now, if I try to compile the above code I get lots of error: type mismatch; found : plg.mvfml.Calculus[E]#Expr required: c.Expr case 0 = new c.Neg(genRndExpr(c, level+1)) And the same happens if I try to do something like: val boolCalc = new Calculus(Bool) val e1: boolCalc.Expr = genRndExpr(boolCalc) Please note that the generator itself is not of concern, but I will need to do similar things (i.e. create and manipulate calculus instance expressions) a lot on the rest of the system. Am I doing something wrong? Is it possible to do what I want to do? Help on this matter is highly needed and appreciated. Thanks a lot in advance.

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  • How to efficiently save changes made in UI/main thread with Core Data?

    - by Jaanus
    So, there have been several posts here about importing and saving data from an external data source into Core Data. Apple documents a reasonable pattern for this: "import and save on background thread, merge saved objects to main thread." All fine and good. I have a related but different problem: the user is modifying data in the UI and main thread, and thus modifies state of some objects in the managed object context (MOC). I would like to save these changes from time to time. What is a good way to do that? Now, you could say that I could do the same: create a background thread with its own MOC and pass the changed objectID-s there. The catch-22 for me with this is that an object's ID changes when it is saved, and I cannot guarantee the order of things happening. I may end up passing a different objectID into the background thread for the same object, based on whether the object has been previously saved or not, and I don't know if Core Data can resolve this and see that different objectID-s are pointing to the same object and not create duplicates for me. (I could test this, but I'm lazywebbing with this question first.) One thought I had: I could always do MOC saves on a background thread, and queue them up with operationqueue, so that there is always only one save in progress. I would not create a new MOC, I would just use the same MOC as in main thread. Now, this is not thread safe and when someone modifies the MOC in main thread while it is being saved in background thread, the results will probably be catastrophic. But, minus the thread safety, you can see what kind of solution I'd wish for. To be clear, the problem I need to fix is that if I just do the save in main thread, it blocks the UI for an unacceptably long period of time, I want to move the save to background thread. So, questions: what about the reasoning of an object ID changing during saving, and Core Data being able to resolve them to the same object? Would this be the right way of addressing this problem? any other good ways of doing this?

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  • C++ scoping error

    - by Pat Murray
    I have the following code: #include "Student.h" #include "SortedList.h" using namespace std; int main() { // points to the sorted list object SortedList *list = new SortedList; //This is line 17 // array to hold 100 student objects Student create[100]; int num = 100000; // holds different ID numbers // fills an array with 100 students of various ID numbers for (Student &x : create) { x = new Student(num); num += 100; } // insert all students into the sorted list for (Student &x : create) list->insert(&x); delete list; return 0; } And I keep getting the compile time error: main.cpp: In function ‘int main()’: main.cpp:17: error: ‘SortedList’ was not declared in this scope main.cpp:17: error: ‘list’ was not declared in this scope main.cpp:17: error: expected type-specifier before ‘SortedList’ main.cpp:17: error: expected `;' before ‘SortedList’ main.cpp:20: error: ‘Student’ was not declared in this scope main.cpp:20: error: expected primary-expression before ‘]’ token main.cpp:20: error: expected `;' before ‘create’ main.cpp:25: error: expected `;' before ‘x’ main.cpp:31: error: expected primary-expression before ‘for’ main.cpp:31: error: expected `;' before ‘for’ main.cpp:31: error: expected primary-expression before ‘for’ main.cpp:31: error: expected `)' before ‘for’ main.cpp:31: error: expected `;' before ‘x’ main.cpp:34: error: type ‘<type error>’ argument given to ‘delete’, expected pointer main.cpp:35: error: expected primary-expression before ‘return’ main.cpp:35: error: expected `)' before ‘return’ My Student.cpp and SortedList.cpp files compile just fine. They both also include .h files. I just do not understand why I get an error on that line. It seems to be a small issue though. Any insight would be appreciated. UPDATE1: I originally had .h files included, but i changed it when trying to figure out the cause of the error. The error remains with the .h files included though. UPDATE2: SortedList.h #ifndef SORTEDLIST_H #define SORTEDLIST_H #include "Student.h" /* * SortedList class * * A SortedList is an ordered collection of Students. The Students are ordered * from lowest numbered student ID to highest numbered student ID. */ class SortedList { public: SortedList(); // Constructs an empty list. SortedList(const SortedList & l); // Constructs a copy of the given student object ~SortedList(); // Destructs the sorted list object const SortedList & operator=(const SortedList & l); // Defines the assignment operator between two sorted list objects bool insert(Student *s); // If a student with the same ID is not already in the list, inserts // the given student into the list in the appropriate place and returns // true. If there is already a student in the list with the same ID // then the list is not changed and false is returned. Student *find(int studentID); // Searches the list for a student with the given student ID. If the // student is found, it is returned; if it is not found, NULL is returned. Student *remove(int studentID); // Searches the list for a student with the given student ID. If the // student is found, the student is removed from the list and returned; // if no student is found with the given ID, NULL is returned. // Note that the Student is NOT deleted - it is returned - however, // the removed list node should be deleted. void print() const; // Prints out the list of students to standard output. The students are // printed in order of student ID (from smallest to largest), one per line private: // Since Listnodes will only be used within the SortedList class, // we make it private. struct Listnode { Student *student; Listnode *next; }; Listnode *head; // pointer to first node in the list static void freeList(Listnode *L); // Traverses throught the linked list and deallocates each node static Listnode *copyList(Listnode *L); // Returns a pointer to the first node within a particular list }; #endif #ifndef STUDENT_H #define STUDENT_H Student.h #ifndef STUDENT_H #define STUDENT_H /* * Student class * * A Student object contains a student ID, the number of credits, and an * overall GPA. */ class Student { public: Student(); // Constructs a default student with an ID of 0, 0 credits, and 0.0 GPA. Student(int ID); // Constructs a student with the given ID, 0 credits, and 0.0 GPA. Student(int ID, int cr, double grPtAv); // Constructs a student with the given ID, number of credits, and GPA.\ Student(const Student & s); // Constructs a copy of another student object ~Student(); // Destructs a student object const Student & operator=(const Student & rhs); // Defines the assignment operator between two student objects // Accessors int getID() const; // returns the student ID int getCredits() const; // returns the number of credits double getGPA() const; // returns the GPA // Other methods void update(char grade, int cr); // Updates the total credits and overall GPA to take into account the // additions of the given letter grade in a course with the given number // of credits. The update is done by first converting the letter grade // into a numeric value (A = 4.0, B = 3.0, etc.). The new GPA is // calculated using the formula: // // (oldGPA * old_total_credits) + (numeric_grade * cr) // newGPA = --------------------------------------------------- // old_total_credits + cr // // Finally, the total credits is updated (to old_total_credits + cr) void print() const; // Prints out the student to standard output in the format: // ID,credits,GPA // Note: the end-of-line is NOT printed after the student information private: int studentID; int credits; double GPA; }; #endif

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  • Good Domain Driven Design samples

    - by jlembke
    I'm learning about DDD and enjoying every minute of it. However, there are some practical issues that are confusing to me that I think seeing some good samples might clear up. So being at peace with those issues, does anyone know of some good working code samples that do a good job of modeling basic DDD concepts? Particularly interested in An illustrative Domain Model Repositories Use of Domain/Application Services Value Objects Aggregate Roots I know I'm probably asking for too much, but anything close will help.

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  • Django debug error

    - by Hulk
    I have the following in my model: class info(models.Model): add = models.CharField(max_length=255) name = models.CharField(max_length=255) An in the views when i say info_l = info.objects.filter(id=1) logging.debug(info_l.name) i get an error saying name doesnt exist at debug statement. 'QuerySet' object has no attribute 'name' 1.How can this be resolved. 2.Also how to query for only one field instead of selecting all like select name from info.

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  • Hibernate - on the stack or on the heap?

    - by Stephano
    As a Java programmer, you usually keep two truths in your pocket: Instance variables and Objects lie on Heap. Local variables and methods lie on the Stack. Now that I use Hibernate in just about everything, I realize I'm not as sure of myself. Are there some good rules of thumb for using hibernate and knowing where your memory lives?

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  • C# what does the == operator do in detail?

    - by clamp
    in c# what does exactly happen in the background when you do a comparison with the "==" operator on two objects? does it just compare the addresses? or does it something like Equals() or CompareTo() ? PS: what about the "==" operator in java? does it behave the same?

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  • class composition instead of object composition?

    - by fayer
    I want a class property to be reference to another class, not its object and then use this property to call the class's static methods. class Database { private static $log; public static function addLog($LogClass) { self::$log = $LogClass; } public static function log() { self::$log::write(); // seems not possible to write it like this } } any suggestions how i can accomplish this? cause i have no reason making them objects, i want to use the classes for it.

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  • Using Apple autorelease pools without Objective-C

    - by PierreBdR
    I am developing an application that needs to work on Linux, Windows and Mac OS X. To that purpose, I am using C++ with Qt. For many reasons, on Mac OS X, I need to use CoreFoundation functions (such as CFBundleCopyBundleURL) that creates core objects that need to be released with CFRelease. But doing so generate a lots of these warnings: *** __NSAutoreleaseNoPool(): Object 0x224f7e0 of class NSURL autoreleased with no pool in place - just leaking All the code I've seen concerning these autorelease pools are written in Objective-C. Does anybody know how to create/use autorelease pools in C or C++?

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  • Fuzzy Regex, Text Processing, Lexical Analysis?

    - by justinzane
    I'm not quite sure what terminology to search for, so my title is funky... Here is the workflow I've got: Semi-structured documents are scanned to file. The files are OCR'd to text. The text is parsed into Python objects The objects are serialized (to SQL, JSON, whatever) for use. The documents are structures like this: HEADER blah blah, Page ### blah Garbage text... 1. Question Text... continued until now. A. Choice text... adsadsf. B. Another Choice... 2. Another Question... I need to extract the questions and choices. The problem is that, because the text is OCR output, there are occasional strange substitutions like '2' - 'Z' which makes ordinary regular expressions useless. I've tried the Levenshtein module and it helps, but it requires prior knowledge of what edit distance is to be expected. I don't know whether I'm looking to create a parser? a lexer? something else? This has lead me down all kinds of interesting but nonrelevant paths. Guidance would be greatly appreciated. Oh, also, the text is generally from specific technical domains, so general spelling tools are not so helpful. Regarding the structure of the documents, there is no clear visual pattern -- like line breaks or indentation -- with the exception of the fact that "questions" usually begin a line. Crap on the document can cause characters to appear before the actual beginning of the line, which means that something along the lines of r'^[0-9]+' does not reliably work. Though the "questions" always begin with an int, a period and a space; the OCR can substitute other characters or skip characters. This is not so much a problem with Tesseract or Cunieform, rather with the poor quality of the paper documents. # Note: for the project in question, it was decided that having a human prep the OCR'd text was better that spending the time coding a solution. I'd still love good pointers, however.

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  • Multiple circles -> One Polygon?

    - by Josh
    Using Google Maps API v3, I was able to create multiple google.maps.Circle objects on my map. However, I now need to "connect" them somehow. I have the following map with multiple circles: I now need to get it to look something like this: I've looked all over the Internet for solutions, but to no avail. Any ideas?

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  • MS SQL Error: Primary file group is full

    - by aximili
    I have a very large table in my database and I am starting to get this error Could not allocate a new page for database 'mydatabase' because of insufficient disk space in filegroup 'PRIMARY'. Create the necessary space by dropping objects in the filegroup, adding additional files to the filegroup, or setting autogrowth on for existing files in the filegroup. How do you fix this error? I don't understand the suggestions there.

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